This invention relates generally to motor vehicle suspension systems. More specifically, the present invention relates to a traction device for limiting wrap-up of a leaf spring on acceleration of a motor vehicle.
Although there are many different types of suspension systems available for use in motor vehicles, the conventional leaf spring is most widely used. In rear-wheel drive vehicles, during acceleration the leaf spring is subject to twisting forces which are opposite in direction and magnitude to the acceleration of the drive wheels. This tends to cause some wrap-up of the rear wheel leaf springs and, under extreme acceleration conditions, often contributes to rear wheel "hop".
In an effort to minimize leaf spring wrap-up and rear wheel "hop" on acceleration, a number of devices have been designed. One of these is the simple bolt-on traction bar. Simple traction bars comprise a straight length of material, generally of steel, with a mounting pad attached to one end and a rubber "snubber" at the other. The mounting pad is attached to the point at which the rear axle meets the leaf spring assembly. The length of the bar extends forward from the mounting pad to a point under the front leaf spring eye. Under acceleration conditions, the counter-rotation of the rear axle is arrested when the snubber meets the spring eye.
Such bolt-on traction bars provide a number of advantages in that they decrease leaf spring wrap-up, tend to prevent rear wheel hop, and aid in improving rear wheel traction during acceleration. Additionally, these traction bars are typically relatively inexpensive and easy to install. They suffer a number of drawbacks, however, in that they have no effect on the instant center (the point at which the rear wheels push the vehicle) , they only offer marginal improvement in traction, and they are only minimally adjustable.
Several other devices have been devised which represent improvements over the bolt-on traction bar. One such device is the ladder bar and another is the 4-link system. The ladder bar device comprises two mounting assemblies. One such mounting assembly is welded to the rear axle housing and the other is welded to the chassis. These mounting assemblies are interconnected by a tubing structure. The 4-link system, on the other hand, eliminates the conventional leaf spring from the motor vehicle. It utilizes two mounts, one of which is welded to the rear axle housing and the other being welded forward on the chassis. Tubular links connect the rear axle housing to the chassis.
Each of these improved devices prevents leaf spring wrap-up and rear wheel hop, greatly improves traction, and permits the instant center to be adjusted forwardly. There are, however, significant disadvantages associates with each of these systems which makes it less than ideal. Typically both the ladder bar and the 4-link system are more expensive than simple bolt-on traction bars. Additionally, professional installation is required.
Accordingly, there has been a need for a novel traction device for motor vehicles which is of durable yet simple construction, may be manufactured efficiently utilizing modern manufacturing techniques, and which provides many of the advantages of the prior ladder bars and 4-link systems in a bolt-on device. Such an improved traction device must be capable of preventing leaf spring wrap-up and rear wheel hop, as well as permitting the vehicle instant center to be moved forwardly. This would have the desirable effect of greatly improving traction during hard acceleration conditions. The present invention fulfills these needs and provides other related advantages.